The present invention relates to a new and improved construction of bobbin tube clamping device for a bobbin chuck for textile bobbins.
Generally speaking, the arrangement of the invention is of the type incorporating a tubular sleeve member for supporting the textile bobbin tube, a chuck member is arranged to be movable within the sleeve member in the axial direction of the bobbin chuck. The chuck member has a guide surface inclined with regard to the lengthwise axis of the bobbin chuck for supporting and displacing in a direction radially of the bobbin chuck a tube clamping element partially protruding to a limited extent through an opening of the tubular sleeve member. Bobbin tube clamping devices of the aforementioned type and others are used primarily in conjunction with winding machines serving to wind endless filaments or the like.
This particular field of technology is already acquainted with different constructions of bobbin tube clamping devices employing tube clamping elements capable of moving radially with respect to the bobbin chuck for the purpose of clamping a bobbin tube which has been placed on to the bobbin chuck.
One state-of-the-art construction teaches the provision of a circular body provided with a circumferential groove for receiving a number of balls, the circular body being slidably arranged in a bobbin chuck having a tubular sleeve member. The groove is formed by two conical surfaces which are differently inclined with respect to the bobbin chuck axis. The surface of less inclination serves as a sliding surface upon which the balls --during axial movement of the circular body -- are moved partially through openings in the sleeve member in such a manner that the balls are pressed in the radial direction with respect to the bobbin chuck against the inner wall of a bobbin tube placed upon the bobbin chuck. In order to prevent the balls from passing through the openings, the openings are adapted in spherical configuration to the ball surface.
A decisive drawback of this state-of-the-art device resides in the fact that the balls must be pressed with considerable force against the inner wall of the bobbin tube in order to be able to take-up the braking moment of a heavy and rapidly rotating full bobbin package, which, as should be evident, either causes undesirable deformations of the bobbin tube or requires considerably stronger and thus more expensive bobbin tubes.
A further drawback resides in the fact that the spherical guide zone prevents rotation of the balls during the time that the bobbin package is braked substantially only by the action of the friction between the ball surface and the guide zone, which also requires high contact pressures and results in a protrusion or departure of the balls which is limited by the openings.
Additionally, the manufacture of such spherical-shaped openings which are provided in such arrangement is both complicated and expensive.